CVE-2025-12106

Critical

Published: 01 December 2025

Published

01 December 2025

Modified

30 December 2025

KEV Added

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Patch

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CVSS Score 9.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H

EPSS Score 0.0007 21.3th percentile

Risk Priority 18 60% EPSS · 20% KEV · 20% CVSS

Summary

CVE-2025-12106 is a critical-severity Buffer Over-read (CWE-126) vulnerability in Openvpn Openvpn. Its CVSS base score is 9.1 (Critical).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 21.3th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

The strongest mitigations our analysis identified are NIST 800-53 SI-10 (Information Input Validation) and SI-2 (Flaw Remediation).

Threat & Defense at a Glance

What attackers do: exploitation maps to Exploit Public-Facing Application (T1190) and 2 other techniques. What defenders deploy: see the NIST 800-53 controls recommended below.

Threat & Defense Details

Mitigating Controls (NIST 800-53 r5)AI

SI-2 Flaw Remediation good match

prevent

Directly requires timely identification, reporting, and correction of the specific heap buffer over-read flaw in OpenVPN during IP address parsing.

SI-10 Information Input Validation good match

prevent

Mandates validation of network information inputs like IP addresses to prevent buffer over-reads from insufficient argument checking.

SI-16 Memory Protection partial match

prevent

Provides memory safeguards such as heap protections that mitigate exploitation of buffer over-read vulnerabilities leading to data exposure or crashes.

MITRE ATT&CK Enterprise TechniquesAI

T1190 Exploit Public-Facing Application Initial Access

Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.

attack.mitre.org →

T1210 Exploitation of Remote Services Lateral Movement

Adversaries may exploit remote services to gain unauthorized access to internal systems once inside of a network.

attack.mitre.org →

T1499.004 Application or System Exploitation Impact

Adversaries may exploit software vulnerabilities that can cause an application or system to crash and deny availability to users.

attack.mitre.org →

Why these techniques?

CVE enables remote unauthenticated exploitation of OpenVPN (public-facing remote service) for heap over-read (info disclosure) and DoS via application crash.

Confidence: HIGH · MITRE ATT&CK Enterprise v19.0

NVD Description

Insufficient argument validation in OpenVPN 2.7_alpha1 through 2.7_rc1 allows an attacker to trigger a heap buffer over-read when parsing IP addresses

Deeper analysisAI

CVE-2025-12106 is a vulnerability caused by insufficient argument validation in OpenVPN versions 2.7_alpha1 through 2.7_rc1. The flaw enables an attacker to trigger a heap buffer over-read during IP address parsing. Published on 2025-12-01, it carries a CVSS v3.1 base score of 9.1 (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H) and maps to CWE-126 (Buffer Over-read).

The vulnerability can be exploited by a remote, unauthenticated attacker over the network with low complexity and no user interaction required. Exploitation leads to high confidentiality impact, potentially allowing sensitive data exposure from heap memory, and high availability impact, such as server crashes or denial of service.

Mitigation details are provided in advisories from the OpenVPN community at https://community.openvpn.net/Security%20Announcements/CVE-2025-12106 and the mailing list announcement at https://www.mail-archive.com/openvpn-announce@lists.sourceforge.net/msg00152.html.